Game Development Reference
Figure 13.3 Zero parallax making visualisation of objects at screen level possible
Figure 13.4 Negative parallax makes visualising objects in front of the screen possible
When part of the virtual object is located at screen level, the homologous points have
zero parallax. They are displayed in the same places (Figure 13.3).
Negative parallax (crossed):
When the object observed is located virtually in front of the screen, the parallax is
negative. The left and right homologous points are displayed to the right and to the
left respectively (Figure 13.4).
As we have previously mentioned, the parallax should be small so as not to create
great difficulties for stereoscopic vision. Otherwise, the brain either cannot merge the
two images or it does it with a certain strain. The objective is therefore to create
stereoscopic images with a low parallax while maintaining an effect of depth. With
reference to experimental studies described previously, the difficulty of merging two
plane images having a parallax angle greater than 1.2 ◦ ,orupto1.5 ◦ was shown for